496 Artlmr Smith Woodward — British Fossil CrocodiUa. 



some schists out of other igneous rocks. It may obliterate an earlier 

 foliation, or it may intensify it, or it may produce an independent 

 and more fissile foliation. 



In this sense gneiss may be said to pass into granite, because 

 a rock which is now, both macroscopically and microscopically, a 

 gneiss, may prove to be a granite which has in some parts yielded to 

 pressure more than in others. 



9. As we pass outwards from the great central granitoid masses, 

 we come to gneisses and schists, where the evidence of some kind of 

 stratification becomes more marked ; bands of crystalline limestone, 

 quartzite, and granulite being associated with mica schist of many 

 kinds — simple, garnetiferous, staurolitic, actinolitic, and the like — 

 the bands of difierent mineral character and composition varying 

 from mere streaks to layers up to many yards in thickness. In fact, 

 the above-named rocks are associated exactly as limestones, sand- 

 stones, and clays ai'e associated in the ordinary sedimentaries. 



10. Although the crushing of a crystalline rock in situ, or the 

 squeezing and shearing of a breccia or conglomerate of crystalline 

 fragments, occasionally gives rise to local difficulties, these are on 

 a small scale, and sedimentary beds belonging to the Palaeozoic or 

 later periods of deposition are generally readily distinguishable from 

 the whole of the crystalline series. Though folded and faulted in 

 the most extraordinary manner, the members of the two series can 

 generally be separated, and in the Alps there is no evidence of a 

 mingling of the one with the other .in the process of rolling out or 

 squeezing together; so that after patient study and microscopic 

 examination we can generally decide without hesitation whether 

 a particular set of rocks has originated from the crystalline or the 

 sedimentary series. I do not say that we can always decide whether 

 a schist or a gneiss has originated from an igneous rock or from au 

 older schist or gneiss, but I think that in the Alps we can say that 

 it has originated from one of these. Fortunately, intrusive rocks are 

 rare in the Paleeozoic and later deposits in this part of the Alps. 



11. Thus, although the Tertiary metaraorphism of the Alpine 

 rocks is very important, it is more pretentious than real, and its 

 effects seem to have been the greatest where it has found a rock 

 already crystalline to act upon. Hence I believe that every true 

 gneiss and schist in the Alps is much older than the Carboniferous, 

 and is probably older than any member of the Palasozoic j)eriod. 



IV. — On the Liteeature and Nomenclature of British Fossil 



Crocodilia. 



By Arthur Smith Woodward, 



of the British Museum (Natural History). 



(With a Folding Table of Genera and Species). 



OF all groups of fossil reptiles, there is perhaps none in greater 

 need of critical revision than that comprising the Crocodilia. 

 The remains of this order already discovered are so nmnerous, and 

 the various descriptive accounts of them so scattered and disconnected, 



